This invention relates generally to belt conveyors and, more particularly, to an extendable conveyor having a base unit, at least two extendable units selectively nested within each other and the base unit, and a conveying member supported by the base unit and any extended portions of the extendable units.
Extendable conveyor units are useful for loading and unloading trailer trucks in order to deliver or retrieve the product at any desired point of the trailer. Such a unit is disclosed in U.S. Pat. No. 3,835,980 issued to Brooks, Jr. for a CONVEYOR WITH EXTENDABLE BOOMS. One important rating of an extendable conveyor is the ratio of the width of the conveying member, such as a driven belt, to the overall width of the stationary base unit. Because each extendable unit, or boom, must be narrower than the next innermost extendable unit, the width of the most remote unit dictates the width of the belt which may be accommodated. Because each extendable unit is cantilevered from the prior unit, the support for each extendable unit must be efficient in order to avoid taking up excessive space and, thus, reducing the width of each extendable unit. Another important rating is the ratio of the fully extended length to the fully retracted length of the conveyor. This results from a desire to minimize the intrusion of the conveyor when it is not in use while maximizing the extended length into the trailer. All of this must be accomplished while providing adequate support at the remote end of a fully extended conveyor with minimum vertical deflection under rated loading. It is further desirable to provide such an extendable conveyor in which the base unit may itself be pivotally adjustable in order to provide vertical adjustability of the remote end of the conveyor.